internal/testenv: treat netbsd-arm*-bsiegert as slow builders

Change-Id: I80f22d6ffdb38085dabba12ec5f53c3e5034d132
Reviewed-on: https://go-review.googlesource.com/c/tools/+/324229
Trust: Bryan C. Mills <bcmills@google.com>
Trust: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Robert Findley <rfindley@google.com>
diff --git a/internal/testenv/testenv.go b/internal/testenv/testenv.go
index 2f7d2a0..49616da 100644
--- a/internal/testenv/testenv.go
+++ b/internal/testenv/testenv.go
@@ -247,7 +247,7 @@
 //
 // It should be called from within a TestMain function.
 func ExitIfSmallMachine() {
-	switch os.Getenv("GO_BUILDER_NAME") {
+	switch b := os.Getenv("GO_BUILDER_NAME"); b {
 	case "linux-arm-scaleway":
 		// "linux-arm" was renamed to "linux-arm-scaleway" in CL 303230.
 		fmt.Fprintln(os.Stderr, "skipping test: linux-arm-scaleway builder lacks sufficient memory (https://golang.org/issue/32834)")
@@ -255,6 +255,11 @@
 	case "plan9-arm":
 		fmt.Fprintln(os.Stderr, "skipping test: plan9-arm builder lacks sufficient memory (https://golang.org/issue/38772)")
 		os.Exit(0)
+	case "netbsd-arm-bsiegert", "netbsd-arm64-bsiegert":
+		// As of 2021-06-02, these builders are running with GO_TEST_TIMEOUT_SCALE=10,
+		// and there is only one of each. We shouldn't waste those scarce resources
+		// running very slow tests.
+		fmt.Fprintf(os.Stderr, "skipping test: %s builder is very slow\n", b)
 	}
 }